net/sched/sch_drr.c

   1 /*
   2  * net/sched/sch_drr.c         Deficit Round Robin scheduler
   3  *
   4  * Copyright (c) 2008 Patrick McHardy <kaber@trash.net>
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License
   8  * version 2 as published by the Free Software Foundation.
   9  */
  10
  11 #include <linux/module.h>
  12 #include <linux/slab.h>
  13 #include <linux/init.h>
  14 #include <linux/errno.h>
  15 #include <linux/netdevice.h>
  16 #include <linux/pkt_sched.h>
  17 #include <net/sch_generic.h>
  18 #include <net/pkt_sched.h>
  19 #include <net/pkt_cls.h>
  20
  21 struct drr_class {
  22         struct Qdisc_class_common       common;
  23         unsigned int                    filter_cnt;
  24
  25         struct gnet_stats_basic_packed          bstats;
  26         struct gnet_stats_queue         qstats;
  27         struct net_rate_estimator __rcu *rate_est;
  28         struct list_head                alist;
  29         struct Qdisc                    *qdisc;
  30
  31         u32                             quantum;
  32         u32                             deficit;
  33 };
  34
  35 struct drr_sched {
  36         struct list_head                active;
  37         struct tcf_proto __rcu          *filter_list;
  38         struct tcf_block                *block;
  39         struct Qdisc_class_hash         clhash;
  40 };
  41
  42 static struct drr_class *drr_find_class(struct Qdisc *sch, u32 classid)
  43 {
  44         struct drr_sched *q = qdisc_priv(sch);
  45         struct Qdisc_class_common *clc;
  46
  47         clc = qdisc_class_find(&q->clhash, classid);
  48         if (clc == NULL)
  49                 return NULL;
  50         return container_of(clc, struct drr_class, common);
  51 }
  52
  53 static const struct nla_policy drr_policy[TCA_DRR_MAX + 1] = {
  54         [TCA_DRR_QUANTUM]       = { .type = NLA_U32 },
  55 };
  56
  57 static int drr_change_class(struct Qdisc *sch, u32 classid, u32 parentid,
  58                             struct nlattr **tca, unsigned long *arg,
  59                             struct netlink_ext_ack *extack)
  60 {
  61         struct drr_sched *q = qdisc_priv(sch);
  62         struct drr_class *cl = (struct drr_class *)*arg;
  63         struct nlattr *opt = tca[TCA_OPTIONS];
  64         struct nlattr *tb[TCA_DRR_MAX + 1];
  65         u32 quantum;
  66         int err;
  67
  68         if (!opt) {
  69                 NL_SET_ERR_MSG(extack, "DRR options are required for this operation");
  70                 return -EINVAL;
  71         }
  72
  73         err = nla_parse_nested_deprecated(tb, TCA_DRR_MAX, opt, drr_policy,
  74                                           extack);
  75         if (err < 0)
  76                 return err;
  77
  78         if (tb[TCA_DRR_QUANTUM]) {
  79                 quantum = nla_get_u32(tb[TCA_DRR_QUANTUM]);
  80                 if (quantum == 0) {
  81                         NL_SET_ERR_MSG(extack, "Specified DRR quantum cannot be zero");
  82                         return -EINVAL;
  83                 }
  84         } else
  85                 quantum = psched_mtu(qdisc_dev(sch));
  86
  87         if (cl != NULL) {
  88                 if (tca[TCA_RATE]) {
  89                         err = gen_replace_estimator(&cl->bstats, NULL,
  90                                                     &cl->rate_est,
  91                                                     NULL,
  92                                                     qdisc_root_sleeping_running(sch),
  93                                                     tca[TCA_RATE]);
  94                         if (err) {
  95                                 NL_SET_ERR_MSG(extack, "Failed to replace estimator");
  96                                 return err;
  97                         }
  98                 }
  99
 100                 sch_tree_lock(sch);
 101                 if (tb[TCA_DRR_QUANTUM])
 102                         cl->quantum = quantum;
 103                 sch_tree_unlock(sch);
 104
 105                 return 0;
 106         }
 107
 108         cl = kzalloc(sizeof(struct drr_class), GFP_KERNEL);
 109         if (cl == NULL)
 110                 return -ENOBUFS;
 111
 112         cl->common.classid = classid;
 113         cl->quantum        = quantum;
 114         cl->qdisc          = qdisc_create_dflt(sch->dev_queue,
 115                                                &pfifo_qdisc_ops, classid,
 116                                                NULL);
 117         if (cl->qdisc == NULL)
 118                 cl->qdisc = &noop_qdisc;
 119         else
 120                 qdisc_hash_add(cl->qdisc, true);
 121
 122         if (tca[TCA_RATE]) {
 123                 err = gen_replace_estimator(&cl->bstats, NULL, &cl->rate_est,
 124                                             NULL,
 125                                             qdisc_root_sleeping_running(sch),
 126                                             tca[TCA_RATE]);
 127                 if (err) {
 128                         NL_SET_ERR_MSG(extack, "Failed to replace estimator");
 129                         qdisc_put(cl->qdisc);
 130                         kfree(cl);
 131                         return err;
 132                 }
 133         }
 134
 135         sch_tree_lock(sch);
 136         qdisc_class_hash_insert(&q->clhash, &cl->common);
 137         sch_tree_unlock(sch);
 138
 139         qdisc_class_hash_grow(sch, &q->clhash);
 140
 141         *arg = (unsigned long)cl;
 142         return 0;
 143 }
 144
 145 static void drr_destroy_class(struct Qdisc *sch, struct drr_class *cl)
 146 {
 147         gen_kill_estimator(&cl->rate_est);
 148         qdisc_put(cl->qdisc);
 149         kfree(cl);
 150 }
 151
 152 static int drr_delete_class(struct Qdisc *sch, unsigned long arg)
 153 {
 154         struct drr_sched *q = qdisc_priv(sch);
 155         struct drr_class *cl = (struct drr_class *)arg;
 156
 157         if (cl->filter_cnt > 0)
 158                 return -EBUSY;
 159
 160         sch_tree_lock(sch);
 161
 162         qdisc_purge_queue(cl->qdisc);
 163         qdisc_class_hash_remove(&q->clhash, &cl->common);
 164
 165         sch_tree_unlock(sch);
 166
 167         drr_destroy_class(sch, cl);
 168         return 0;
 169 }
 170
 171 static unsigned long drr_search_class(struct Qdisc *sch, u32 classid)
 172 {
 173         return (unsigned long)drr_find_class(sch, classid);
 174 }
 175
 176 static struct tcf_block *drr_tcf_block(struct Qdisc *sch, unsigned long cl,
 177                                        struct netlink_ext_ack *extack)
 178 {
 179         struct drr_sched *q = qdisc_priv(sch);
 180
 181         if (cl) {
 182                 NL_SET_ERR_MSG(extack, "DRR classid must be zero");
 183                 return NULL;
 184         }
 185
 186         return q->block;
 187 }
 188
 189 static unsigned long drr_bind_tcf(struct Qdisc *sch, unsigned long parent,
 190                                   u32 classid)
 191 {
 192         struct drr_class *cl = drr_find_class(sch, classid);
 193
 194         if (cl != NULL)
 195                 cl->filter_cnt++;
 196
 197         return (unsigned long)cl;
 198 }
 199
 200 static void drr_unbind_tcf(struct Qdisc *sch, unsigned long arg)
 201 {
 202         struct drr_class *cl = (struct drr_class *)arg;
 203
 204         cl->filter_cnt--;
 205 }
 206
 207 static int drr_graft_class(struct Qdisc *sch, unsigned long arg,
 208                            struct Qdisc *new, struct Qdisc **old,
 209                            struct netlink_ext_ack *extack)
 210 {
 211         struct drr_class *cl = (struct drr_class *)arg;
 212
 213         if (new == NULL) {
 214                 new = qdisc_create_dflt(sch->dev_queue, &pfifo_qdisc_ops,
 215                                         cl->common.classid, NULL);
 216                 if (new == NULL)
 217                         new = &noop_qdisc;
 218         }
 219
 220         *old = qdisc_replace(sch, new, &cl->qdisc);
 221         return 0;
 222 }
 223
 224 static struct Qdisc *drr_class_leaf(struct Qdisc *sch, unsigned long arg)
 225 {
 226         struct drr_class *cl = (struct drr_class *)arg;
 227
 228         return cl->qdisc;
 229 }
 230
 231 static void drr_qlen_notify(struct Qdisc *csh, unsigned long arg)
 232 {
 233         struct drr_class *cl = (struct drr_class *)arg;
 234
 235         list_del(&cl->alist);
 236 }
 237
 238 static int drr_dump_class(struct Qdisc *sch, unsigned long arg,
 239                           struct sk_buff *skb, struct tcmsg *tcm)
 240 {
 241         struct drr_class *cl = (struct drr_class *)arg;
 242         struct nlattr *nest;
 243
 244         tcm->tcm_parent = TC_H_ROOT;
 245         tcm->tcm_handle = cl->common.classid;
 246         tcm->tcm_info   = cl->qdisc->handle;
 247
 248         nest = nla_nest_start_noflag(skb, TCA_OPTIONS);
 249         if (nest == NULL)
 250                 goto nla_put_failure;
 251         if (nla_put_u32(skb, TCA_DRR_QUANTUM, cl->quantum))
 252                 goto nla_put_failure;
 253         return nla_nest_end(skb, nest);
 254
 255 nla_put_failure:
 256         nla_nest_cancel(skb, nest);
 257         return -EMSGSIZE;
 258 }
 259
 260 static int drr_dump_class_stats(struct Qdisc *sch, unsigned long arg,
 261                                 struct gnet_dump *d)
 262 {
 263         struct drr_class *cl = (struct drr_class *)arg;
 264         __u32 qlen = qdisc_qlen_sum(cl->qdisc);
 265         struct Qdisc *cl_q = cl->qdisc;
 266         struct tc_drr_stats xstats;
 267
 268         memset(&xstats, 0, sizeof(xstats));
 269         if (qlen)
 270                 xstats.deficit = cl->deficit;
 271
 272         if (gnet_stats_copy_basic(qdisc_root_sleeping_running(sch),
 273                                   d, NULL, &cl->bstats) < 0 ||
 274             gnet_stats_copy_rate_est(d, &cl->rate_est) < 0 ||
 275             gnet_stats_copy_queue(d, cl_q->cpu_qstats, &cl_q->qstats, qlen) < 0)
 276                 return -1;
 277
 278         return gnet_stats_copy_app(d, &xstats, sizeof(xstats));
 279 }
 280
 281 static void drr_walk(struct Qdisc *sch, struct qdisc_walker *arg)
 282 {
 283         struct drr_sched *q = qdisc_priv(sch);
 284         struct drr_class *cl;
 285         unsigned int i;
 286
 287         if (arg->stop)
 288                 return;
 289
 290         for (i = 0; i < q->clhash.hashsize; i++) {
 291                 hlist_for_each_entry(cl, &q->clhash.hash[i], common.hnode) {
 292                         if (arg->count < arg->skip) {
 293                                 arg->count++;
 294                                 continue;
 295                         }
 296                         if (arg->fn(sch, (unsigned long)cl, arg) < 0) {
 297                                 arg->stop = 1;
 298                                 return;
 299                         }
 300                         arg->count++;
 301                 }
 302         }
 303 }
 304
 305 static struct drr_class *drr_classify(struct sk_buff *skb, struct Qdisc *sch,
 306                                       int *qerr)
 307 {
 308         struct drr_sched *q = qdisc_priv(sch);
 309         struct drr_class *cl;
 310         struct tcf_result res;
 311         struct tcf_proto *fl;
 312         int result;
 313
 314         if (TC_H_MAJ(skb->priority ^ sch->handle) == 0) {
 315                 cl = drr_find_class(sch, skb->priority);
 316                 if (cl != NULL)
 317                         return cl;
 318         }
 319
 320         *qerr = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
 321         fl = rcu_dereference_bh(q->filter_list);
 322         result = tcf_classify(skb, fl, &res, false);
 323         if (result >= 0) {
 324 #ifdef CONFIG_NET_CLS_ACT
 325                 switch (result) {
 326                 case TC_ACT_QUEUED:
 327                 case TC_ACT_STOLEN:
 328                 case TC_ACT_TRAP:
 329                         *qerr = NET_XMIT_SUCCESS | __NET_XMIT_STOLEN;
 330                         /* fall through */
 331                 case TC_ACT_SHOT:
 332                         return NULL;
 333                 }
 334 #endif
 335                 cl = (struct drr_class *)res.class;
 336                 if (cl == NULL)
 337                         cl = drr_find_class(sch, res.classid);
 338                 return cl;
 339         }
 340         return NULL;
 341 }
 342
 343 static int drr_enqueue(struct sk_buff *skb, struct Qdisc *sch,
 344                        struct sk_buff **to_free)
 345 {
 346         unsigned int len = qdisc_pkt_len(skb);
 347         struct drr_sched *q = qdisc_priv(sch);
 348         struct drr_class *cl;
 349         int err = 0;
 350         bool first;
 351
 352         cl = drr_classify(skb, sch, &err);
 353         if (cl == NULL) {
 354                 if (err & __NET_XMIT_BYPASS)
 355                         qdisc_qstats_drop(sch);
 356                 __qdisc_drop(skb, to_free);
 357                 return err;
 358         }
 359
 360         first = !cl->qdisc->q.qlen;
 361         err = qdisc_enqueue(skb, cl->qdisc, to_free);
 362         if (unlikely(err != NET_XMIT_SUCCESS)) {
 363                 if (net_xmit_drop_count(err)) {
 364                         cl->qstats.drops++;
 365                         qdisc_qstats_drop(sch);
 366                 }
 367                 return err;
 368         }
 369
 370         if (first) {
 371                 list_add_tail(&cl->alist, &q->active);
 372                 cl->deficit = cl->quantum;
 373         }
 374
 375         sch->qstats.backlog += len;
 376         sch->q.qlen++;
 377         return err;
 378 }
 379
 380 static struct sk_buff *drr_dequeue(struct Qdisc *sch)
 381 {
 382         struct drr_sched *q = qdisc_priv(sch);
 383         struct drr_class *cl;
 384         struct sk_buff *skb;
 385         unsigned int len;
 386
 387         if (list_empty(&q->active))
 388                 goto out;
 389         while (1) {
 390                 cl = list_first_entry(&q->active, struct drr_class, alist);
 391                 skb = cl->qdisc->ops->peek(cl->qdisc);
 392                 if (skb == NULL) {
 393                         qdisc_warn_nonwc(__func__, cl->qdisc);
 394                         goto out;
 395                 }
 396
 397                 len = qdisc_pkt_len(skb);
 398                 if (len <= cl->deficit) {
 399                         cl->deficit -= len;
 400                         skb = qdisc_dequeue_peeked(cl->qdisc);
 401                         if (unlikely(skb == NULL))
 402                                 goto out;
 403                         if (cl->qdisc->q.qlen == 0)
 404                                 list_del(&cl->alist);
 405
 406                         bstats_update(&cl->bstats, skb);
 407                         qdisc_bstats_update(sch, skb);
 408                         qdisc_qstats_backlog_dec(sch, skb);
 409                         sch->q.qlen--;
 410                         return skb;
 411                 }
 412
 413                 cl->deficit += cl->quantum;
 414                 list_move_tail(&cl->alist, &q->active);
 415         }
 416 out:
 417         return NULL;
 418 }
 419
 420 static int drr_init_qdisc(struct Qdisc *sch, struct nlattr *opt,
 421                           struct netlink_ext_ack *extack)
 422 {
 423         struct drr_sched *q = qdisc_priv(sch);
 424         int err;
 425
 426         err = tcf_block_get(&q->block, &q->filter_list, sch, extack);
 427         if (err)
 428                 return err;
 429         err = qdisc_class_hash_init(&q->clhash);
 430         if (err < 0)
 431                 return err;
 432         INIT_LIST_HEAD(&q->active);
 433         return 0;
 434 }
 435
 436 static void drr_reset_qdisc(struct Qdisc *sch)
 437 {
 438         struct drr_sched *q = qdisc_priv(sch);
 439         struct drr_class *cl;
 440         unsigned int i;
 441
 442         for (i = 0; i < q->clhash.hashsize; i++) {
 443                 hlist_for_each_entry(cl, &q->clhash.hash[i], common.hnode) {
 444                         if (cl->qdisc->q.qlen)
 445                                 list_del(&cl->alist);
 446                         qdisc_reset(cl->qdisc);
 447                 }
 448         }
 449         sch->qstats.backlog = 0;
 450         sch->q.qlen = 0;
 451 }
 452
 453 static void drr_destroy_qdisc(struct Qdisc *sch)
 454 {
 455         struct drr_sched *q = qdisc_priv(sch);
 456         struct drr_class *cl;
 457         struct hlist_node *next;
 458         unsigned int i;
 459
 460         tcf_block_put(q->block);
 461
 462         for (i = 0; i < q->clhash.hashsize; i++) {
 463                 hlist_for_each_entry_safe(cl, next, &q->clhash.hash[i],
 464                                           common.hnode)
 465                         drr_destroy_class(sch, cl);
 466         }
 467         qdisc_class_hash_destroy(&q->clhash);
 468 }
 469
 470 static const struct Qdisc_class_ops drr_class_ops = {
 471         .change         = drr_change_class,
 472         .delete         = drr_delete_class,
 473         .find           = drr_search_class,
 474         .tcf_block      = drr_tcf_block,
 475         .bind_tcf       = drr_bind_tcf,
 476         .unbind_tcf     = drr_unbind_tcf,
 477         .graft          = drr_graft_class,
 478         .leaf           = drr_class_leaf,
 479         .qlen_notify    = drr_qlen_notify,
 480         .dump           = drr_dump_class,
 481         .dump_stats     = drr_dump_class_stats,
 482         .walk           = drr_walk,
 483 };
 484
 485 static struct Qdisc_ops drr_qdisc_ops __read_mostly = {
 486         .cl_ops         = &drr_class_ops,
 487         .id             = "drr",
 488         .priv_size      = sizeof(struct drr_sched),
 489         .enqueue        = drr_enqueue,
 490         .dequeue        = drr_dequeue,
 491         .peek           = qdisc_peek_dequeued,
 492         .init           = drr_init_qdisc,
 493         .reset          = drr_reset_qdisc,
 494         .destroy        = drr_destroy_qdisc,
 495         .owner          = THIS_MODULE,
 496 };
 497
 498 static int __init drr_init(void)
 499 {
 500         return register_qdisc(&drr_qdisc_ops);
 501 }
 502
 503 static void __exit drr_exit(void)
 504 {
 505         unregister_qdisc(&drr_qdisc_ops);
 506 }
 507
 508 module_init(drr_init);
 509 module_exit(drr_exit);
 510 MODULE_LICENSE("GPL");